1. Field of the Invention
This invention relates to a method for the manufacture of a coating on a grinding tool.
2. Discussion of the Related Art
It is known that grinding tool can be provided with a coating, for example a diamond layer. Here the surface morphology of the coating is invariably modified in such a way that a smooth layer is deposited on the body. To create an appropriate cutting space for the grinding, the body is given a structure, for example, an external thread. The diamond layer deposited on the body, being a smooth layer, has the tack of providing protection against wear and a cutting material for the machining, for as a rule stable cutting edges and low coefficients of friction are required.
In this connection DE 43 39 326 A1 disclosed a dressing roll and not a grinding tool for grinding wheels. The body of the dressing roll is given a thread profile having a depth of teeth of about 1 mm. Onto this are vapor deposited diamond layers having a thickness of 50 .mu.m to 500 .mu.m. This smooth diamond layer together with the threads forms cutting edges for the dressing roll and there is sufficient cutting space in the indentations in the threads.
The use of an abrasive layer containing individual diamond granules in a metallic binder phase is also known. The binder phase can be applied galvanically and, besides anchoring the diamond granules, provides for the intended amount of wearing away. The cutting space in these tools is formed because the because the binder phase wears away and the diamond granules then have an excess length in relation to the latter. The profiling of these tools is very time-consuming and requires much experience.
A method of treating surface by means of a plasma-enhanced deposition of diamond layers is known from WO 96/41897 A2. The theoretical possibility of producing grinding wheels in this way is mentioned in that document.
WO 96/30557 A1 also mentions the possibility of depositing diamond onto a grinding tool by means of a plasma-enhanced coating process.
Neither document gives any practical information at all as to whether it is in fact possible to produce a grinding tool in this way; it is very doubtful whether a precise definition of properties of the grinding tool to be produced by plasma-enhanced processes can be achieved.